Photoelectric detector and manufacturing method thereof

Abstract

The invention discloses a photoelectric detector and a manufacturing method thereof, and belongs to the technical field of photoelectric detectors. The DBR structure is located on the substrate, the DBR structure comprises a plurality of groups of first dielectric layers and second dielectric layers which are alternately stacked, air gaps are formed in the first dielectric layers through wet chemical etching, and a certain etching selection ratio exists between the first dielectric layers and the second dielectric layers; the functional device structure comprises a P-type InP layer, an absorption layer and an N-type InP layer which are sequentially arranged from top to bottom, and the N-type InP layer is located at the top of the DBR structure. According to the detector enhanced absorption structure based on the air DBR, the responsivity can be improved under the condition that the thickness of a detector absorption area is not increased, the problem that a traditional DBR structure based on a semiconductor material needs to introduce a thick epitaxial layer is solved, and the detector enhanced absorption structure can be widely applied to design of various photoelectric detectors.

Description

Technical Field

[0001] The present invention relates to the technical field of photoelectric detectors, and in particular to a photoelectric detector and a manufacturing method thereof. Background Art

[0002] With the development of modern mobile Internet, the amount of information transmission is growing exponentially. Electrical interconnection has shown its limitations and is unable to meet the bandwidth and rate requirements of massive data transmission in information systems. Optical interconnection uses photons as the information transmission medium. With its advantages of low loss and large bandwidth, it has gradually replaced electrical interconnection and become the mainstream technology for medium and long-distance low-loss transmission. A complete optical interconnection communication system consists of an optical transmitter, an optical transmission link, and an optical receiver, among which the photodetector (PD) is the core device of the optical receiver.

[0003] The performance of a photodetector is usually determined by the degree of light absorption in the absorption region, which is the region of the photodetector where photons are absorbed and converted into electron-hole pairs, and the carrier transit time, which is the time it takes for the generated electrons and holes to move from the absorption region to the detector's electrodes.

[0004] Generally speaking, the thicker the absorption region, the longer the distance light travels in the material, so more photons can be absorbed. This helps to improve the quantum efficiency of the detector (that is, the efficiency of converting photons into electrical signals), especially in the long wavelength range, where the absorption coefficient of photons is low and a larger absorption thickness is required to achieve effective absorption. The absorption process can be described by the following exponential decay formula:

[0005] I(x)=I0e -αz

[0006] Among them, I(x) is the light intensity at depth x, I0 is the arc of the incident light, α is the absorption coefficient of the material, and x is the thickness of the absorption zone. To ensure that the light energy is fully absorbed, the thickness should match the absorption coefficient and the photon energy. However, too thick an absorption zone can also have negative effects, mainly manifested as follows: when the thickness of the absorption zone increases, the generated electrons and holes take longer to move from the absorption zone to the electrode and then be collected, and the carrier transmission time increases, which will increase the response time and cause the speed of the detector to decrease; when the thickness of the absorption zone increases, the drift and diffusion time of the carriers becomes longer, which limits the frequency response range of the detector.

[0007] When designing high-speed photodetectors, an optimal balance must be found between the absorption region thickness and the carrier transmission time to achieve high efficiency and fast response. Usually, when designing the absorption region thickness, it is necessary to consider the device structure and usage scenario of the photodetector itself in order to perform targeted optimization. Therefore, conventional solutions such as introducing electric fields and adjusting the selected materials are complex in design and not universal.

[0008] It should be noted that the information disclosed in the background technology section of the invention is only intended to deepen the understanding of the general background technology of the invention, and should not be regarded as an admission or suggestion in any form that the information constitutes prior art already known to those skilled in the art. Summary of the invention

[0009] The object of the present invention is to provide a photoelectric detector and a method for manufacturing the same, so as to solve the problem that conventional design schemes are complex in design and lack universal applicability.

[0010] In order to solve the above technical problems, the present invention provides a photoelectric detector, comprising:

[0011] substrate;

[0012] A DBR structure, located on the substrate, the DBR structure comprises a plurality of groups of first dielectric layers and second dielectric layers alternately stacked, an air gap is further provided in the first dielectric layer, and a certain etching selectivity ratio exists between the first dielectric layer and the second dielectric layer;

[0013] The functional device structure comprises a P-type InP layer, an absorption layer and an N-type InP layer which are arranged in sequence from top to bottom, wherein the N-type InP layer is located on the top of the DBR structure.

[0014] Preferably, the substrate and the second dielectric layer are made of the same material, both InP.

[0015] Preferably, the first dielectric layer is made of InAlGaAs.

[0016] Preferably, the thickness of the DBR structure is less than 1 μm.

[0017] Preferably, the absorption layer is made of InGaAs.

[0018] A method for manufacturing a photoelectric detector, comprising:

[0019] Providing a substrate, on which a plurality of groups of alternately stacked first dielectric layers and second dielectric layers are formed, and a certain etching selectivity ratio exists between the first dielectric layers and the second dielectric layers;

[0020] Sequentially depositing an N-type InP layer, an absorption layer, and a P-type InP layer on top of the multiple groups of alternately stacked first dielectric layers and second dielectric layers, and sequentially etching the P-type InP layer, the absorption layer, and a portion of the N-type InP layer to form a desired columnar structure for forming a functional device structure;

[0021] A photoresist is covered at least on the functional device structure, the multiple groups of alternately stacked first dielectric layers and second dielectric layers are etched, and the first dielectric layer is selectively etched to form an air gap, so as to form a DBR structure.

[0022] Preferably, the substrate and the second dielectric layer are made of the same material, both InP.

[0023] Preferably, the first dielectric layer is made of InAlGaAs.

[0024] Preferably, the absorption layer is made of InGaAs.

[0025] Preferably, the thickness of the DBR structure is less than 1 μm.

[0026] In the photodetector provided by the present invention, a detector enhanced absorption structure based on air DBR is proposed, and the functional device structure is arranged above the DBR structure, so that the transmission speed of the carriers is guaranteed while the thickness of the absorption layer, that is, the absorption region, remains unchanged, and the overall thickness of the DBR structure is reduced, thereby avoiding the problem that a thicker epitaxial layer needs to be introduced in the traditional DBR structure based on semiconductor materials. The present invention can be widely used in the design of various photodetectors.

[0027] The method for manufacturing the photodetector provided by the present invention and the photodetector provided by the present invention belong to the same inventive concept, therefore, the method for manufacturing the photodetector provided by the present invention has at least all the advantages of the photodetector provided by the present invention, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Those skilled in the art will appreciate that the accompanying drawings are provided for a better understanding of the present invention and do not constitute any limitation on the scope of the present invention.

[0029] Figure 1 is a schematic structural diagram of alternating first dielectric layers and second dielectric layers according to an embodiment of the present invention;

[0030] Figure 2 is a schematic diagram of a film structure formed in one embodiment of the present invention;

[0031] Figure 3 is a schematic diagram of the structure of a functional device according to an embodiment of the present invention;

[0032] Figure 4 is a schematic diagram of an air gap structure formed in one embodiment of the present invention;

[0033] Figure 5 is a flow chart of an embodiment of the present invention.

[0034] In the attached figure:

[0035] 100, substrate; 200, DBR structure; 201, first dielectric layer; 202, second dielectric layer; 203, air gap; 300, functional device structure; 301, N-type InP layer; 302, absorption layer; 303, P-type InP layer. DETAILED DESCRIPTION

[0036] In order to make the purpose, advantages and features of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In addition, the structure shown in the drawings is often a part of the actual structure. In particular, the emphasis of each drawing is different, and sometimes different scales are used.

[0037] As used in the present invention, the singular forms "a", "an" and "the" include plural objects, the term "or" is generally used in a sense including "and / or", the term "several" is generally used in a sense including "at least one", and the term "at least two" is generally used in a sense including "two or more". In addition, the terms "first", "second" and "third" are used for descriptive purposes only and cannot be understood as indicating or suggesting relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second", and "third" may explicitly or implicitly include one or at least two of the features. The term "proximal end" is usually the end close to the operator, and the term "distal end" is usually the end close to the patient. "One end" and "the other end" as well as "proximal end" and "distal end" usually refer to two corresponding parts, which include not only the endpoints. The terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral body; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal connection of the two elements or the interaction relationship between the two elements. In addition, as used in the present invention, an element is arranged on another element, which usually only means that there is a connection, coupling, matching or transmission relationship between the two elements, and the connection, coupling, matching or transmission between the two elements can be direct or indirect through an intermediate element, and it cannot be understood as indicating or implying the spatial position relationship between the two elements, that is, one element can be in any position such as inside, outside, above, below or on one side of another element, unless the content clearly indicates otherwise. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] The inventors have found that the thickness of the absorption region not only affects the efficiency of its photoelectric conversion but also the drift and diffusion time of the carriers. Therefore, when designing a photoelectric sensor, the thickness design of the absorption region needs to balance the above two parameters to achieve high efficiency and fast response.

[0039] The inventors further discovered that the thickness of the absorption zone is usually optimized according to the working wavelength, material absorption coefficient and performance requirements of the detector. For example, long-wavelength detectors with lower absorption coefficients (such as infrared detectors) require thicker absorption zones, while for visible light or ultraviolet light detectors, the absorption zone can be set thinner. Alternatively, the use of high-mobility semiconductor materials (such as gallium arsenide and indium phosphide) can increase the drift velocity of carriers and reduce transmission time, thereby allowing the use of slightly thicker absorption zones without sacrificing speed, and even introducing appropriate electric fields in the absorption zones to ensure that carriers can drift quickly to the electrodes. However, the above scheme needs to consider the device structure and usage scenarios of the photodetector itself in order to perform targeted optimization, and therefore is not universal.

[0040] Based on this, the core idea of ​​the present invention is to propose a detector enhanced absorption structure based on air DBR (distributed Bragg reflector), and set the functional device structure above the DBR structure, so that the absorption layer, that is, the absorption area, can ensure the transmission speed of carriers while keeping the thickness unchanged; compared with the DBR structure based on the alternating growth of two semiconductor materials, the structure based on air DBR can greatly reduce the epitaxial thickness of the DBR layer and the overall thickness of the epitaxial wafer, avoiding the problem that the traditional DBR structure based on semiconductor materials needs to introduce a thicker epitaxial layer, and can be widely used in various photoelectric detector designs.

[0041] For details, please refer to Figure 1-Figure 5 , which is a schematic diagram of an embodiment of the present invention. Figure 4 As shown, a photoelectric detector comprises:

[0042] Substrate 100;

[0043] The DBR structure 200 is located on the substrate 100. The DBR structure 200 includes a plurality of groups of first dielectric layers 201 and second dielectric layers 202 that are alternately stacked. An air gap 203 is also provided in the first dielectric layer 201. A certain etching selectivity ratio exists between the first dielectric layer 201 and the second dielectric layer 202.

[0044] The functional device structure 300 includes a P-type InP layer 303 , an absorption layer 302 , and an N-type InP layer 301 arranged in sequence from top to bottom. The N-type InP layer 301 is located on the top of the DBR structure 200 .

[0045] In one embodiment, the functional device structure 300 is disposed above the DBR structure 200, so that the absorption layer 302, i.e., the absorption region, can ensure the transmission speed of carriers without changing its thickness, and improve the responsivity without increasing the thickness of the absorption region of the detector, which can be widely used in various photodetector designs. The overall thickness of the DBR structure 200 can be made thinner without affecting the propagation of light, thereby avoiding the problem of introducing an additional epitaxial layer of several microns in the traditional DBR structure based on semiconductor materials.

[0046] It should be noted that, since there is a certain etching selectivity ratio between the first dielectric layer 201 and the second dielectric layer 202, the multiple groups of alternating stacked first dielectric layers 201 and second dielectric layers 202 are etched to form a desired shape through the photoresist-encapsulated functional device structure 300. Photoresist can be coated on the second dielectric layer 202 and the periphery of the first dielectric layer 201, and the central area of ​​the first dielectric layer 201 can be selectively etched to form an air gap 203, for example, by wet chemical etching of the central area of ​​the first dielectric layer 201.

[0047] Exemplarily, the thickness of the DBR structure 200 is less than 1 μm. The overall thickness of the DBR structure 200 is, for example, 500 nm to 600 nm. The first dielectric layer 201 and the second dielectric layer 202 are made of materials with different refractive indices, and there is a certain etching selectivity between the first dielectric layer 201 and the second dielectric layer 202. The first dielectric layer 201 and the second dielectric layer 202 generally adopt a DBR structure 200 combination of InP / InAlGaAs. Based on a wet solution of HCl:H3PO3=4:1, the corrosion rate of InP is 800 nm / min, and when etching to form the air gap 203, the second dielectric layer 202 is almost not consumed.

[0048] In one embodiment, the substrate 100 and the second dielectric layer 202 are made of the same material, InP. The first dielectric layer 201 is made of InAlGaAs. The absorption layer 302 is made of InGaAs.

[0049] Based on the same technical concept, the present disclosure also provides a method for manufacturing a photoelectric detector, such as Figure 5 As shown, including:

[0050] S1, such as Figure 1 As shown, a substrate 100 is provided, and a plurality of groups of alternately stacked first dielectric layers 201 and second dielectric layers 202 are formed on the substrate 100, and a certain etching selectivity ratio exists between the first dielectric layers 201 and the second dielectric layers 202.

[0051] S2, such as Figure 2-Figure 3As shown, an N-type InP layer 301, an absorption layer 302 and a P-type InP layer 303 are sequentially deposited on top of the multiple groups of alternately stacked first dielectric layers 201 and second dielectric layers 202, and the P-type InP layer 303, the absorption layer 302 and a portion of the N-type InP layer 301 are sequentially etched to form the desired columnar structure for forming a functional device structure 300.

[0052] The top surface of the N-type InP layer 301 is connected to the absorption layer 302 , and the bottom of the N-type InP layer 301 is not etched, and is connected to the second dielectric layer 202 at the top of the DBR structure 200 through the step structure at the bottom.

[0053] S3, such as Figure 4 As shown, at least the functional device structure 300 is covered with a photoresist, the multiple groups of alternately stacked first dielectric layers 201 and second dielectric layers 202 are etched, and the first dielectric layer 201 is selectively etched to form an air gap 203 to form a DBR structure 200.

[0054] Specifically, the substrate 100 and the second dielectric layer 202 are made of the same material, InP, and the first dielectric layer 201 is made of InAlGaAs. The absorption layer 302 is made of InGaAs.

[0055] Exemplarily, the thickness of the DBR structure 200 is less than 1 μm. The overall thickness of the DBR structure 200 is, for example, 500 nm to 600 nm. The first dielectric layer 201 and the second dielectric layer 202 are made of materials with different refractive indices, and there is a certain etching selectivity between the first dielectric layer 201 and the second dielectric layer 202. When etching to form the air gap 203, the second dielectric layer 202 is almost not consumed. The DBR structure 200 is formed directly by etching the central area of ​​the first dielectric layer 201, which reduces the overall thickness of the DBR structure 200 and ensures the transmission speed of carriers, thereby avoiding the problem that a thicker epitaxial layer is required in a traditional DBR structure based on semiconductor materials.

[0056] In one embodiment, after the columnar structure is formed, a passivation layer (not shown) is deposited on the side walls of the N-type InP layer 301, the absorption layer 302 and the P-type InP layer 303 to reduce the surface recombination current of the device. The material of the passivation layer is, for example, an insulating medium SiO2, Si3N4, HfO2 or Al2O3.

[0057] In the detector enhanced absorption structure based on air DBR and its manufacturing method provided by the present disclosure, the functional device structure 300 is arranged above the DBR structure 200, so that the absorption layer 302, that is, the absorption region, can ensure the transmission speed of carriers without changing the thickness, and improve the responsivity without increasing the thickness of the absorption region of the detector, which can be widely used in various photoelectric detector designs. The DBR structure 200 is formed directly by etching the first dielectric layer 201, which reduces the overall thickness of the DBR structure 200 and ensures the transmission speed of carriers, avoiding the problem that the traditional DBR structure based on semiconductor materials needs to introduce a thicker epitaxial layer.

[0058] The above description is only a description of the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of protection of the technical solution of the present invention.

Claims

1. A photoelectric detector, characterized in that: include: substrate; A DBR structure, located on the substrate, the DBR structure comprises a plurality of groups of first dielectric layers and second dielectric layers alternately stacked, an air gap is further provided in the first dielectric layer, and a certain etching selectivity ratio exists between the first dielectric layer and the second dielectric layer; The functional device structure comprises a P-type InP layer, an absorption layer and an N-type InP layer which are arranged in sequence from top to bottom, wherein the N-type InP layer is located on the top of the DBR structure.

2. The photodetector according to claim 1, characterized in that: The substrate and the second dielectric layer are made of the same material, which is InP.

3. The photodetector according to claim 1, characterized in that: The material of the first dielectric layer is InAlGaAs.

4. The photodetector according to claim 1, characterized in that: The thickness of the DBR structure is less than 1 μm.

5. The photodetector according to claim 1, characterized in that: The material of the absorption layer is InGaAs.

6. A method for manufacturing a photoelectric detector, characterized in that: include: Providing a substrate, on which a plurality of groups of alternately stacked first dielectric layers and second dielectric layers are formed, and a certain etching selectivity ratio exists between the first dielectric layers and the second dielectric layers; Sequentially depositing an N-type InP layer, an absorption layer, and a P-type InP layer on top of the plurality of groups of alternately stacked first dielectric layers and second dielectric layers, and sequentially etching the P-type InP layer, the absorption layer, and a portion of the N-type InP layer to form a desired columnar structure for forming a functional device structure; A photoresist is covered at least on the functional device structure, the multiple groups of alternately stacked first dielectric layers and second dielectric layers are etched, and the first dielectric layer is selectively etched to form an air gap, so as to form a DBR structure.

7. The method for manufacturing a photodetector according to claim 6, characterized in that: The substrate and the second dielectric layer are made of the same material, which is InP.

8. The method for manufacturing a photodetector according to claim 6, characterized in that: The material of the first dielectric layer is InAlGaAs.

9. The method for manufacturing a photodetector according to claim 6, characterized in that: The thickness of the DBR structure is less than 1 μm.

10. The method for manufacturing a photodetector according to claim 6, characterized in that: The material of the absorption layer is InGaAs.

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